Uemura Kengo, Farner Katherine C, Hashimoto Tadafumi, Nasser-Ghodsi Navine, Wolfe Michael S, Koo Edward H, Hyman Bradley T, Berezovska Oksana
1] Alzheimer Research Unit, MassGeneral Institute for Neurodegenerative Diseases, Massachusetts General Hospital, Charlestown, Massachusetts 02129, USA. [2].
Nat Commun. 2010 Nov 30;1:130. doi: 10.1038/ncomms1129.
γ-Secretase generates the peptides of Alzheimer's disease, Aβ(40) and Aβ(42), by cleaving the amyloid precursor protein within its transmembrane domain. γ-Secretase also cleaves numerous other substrates, raising concerns about γ-secretase inhibitor off-target effects. Another important class of drugs, γ-secretase modulators, alter the cleavage site of γ-secretase on amyloid precursor protein, changing the Aβ(42)/Aβ(40) ratio, and are thus a promising therapeutic approach for Alzheimer's disease. However, the target for γ-secretase modulators is uncertain, with some data suggesting that they function on γ-secretase, whereas others support their binding to the amyloid precursor. In this paper we address this controversy by using a fluorescence resonance energy transfer-based assay to examine whether γ-secretase modulators alter Presenilin-1/γ-secretase conformation in intact cells in the absence of its natural substrates such as amyloid precursor protein and Notch. We report that the γ-secretase allosteric site is located within the γ-secretase complex, but substrate docking is needed for γ-secretase modulators to access this site.
γ-分泌酶通过在跨膜结构域内切割淀粉样前体蛋白生成阿尔茨海默病的肽段Aβ(40)和Aβ(42)。γ-分泌酶还切割许多其他底物，这引发了对γ-分泌酶抑制剂脱靶效应的担忧。另一类重要药物γ-分泌酶调节剂，可改变γ-分泌酶在淀粉样前体蛋白上的切割位点，改变Aβ(42)/Aβ(40)比值，因此是一种有前景的阿尔茨海默病治疗方法。然而，γ-分泌酶调节剂的作用靶点尚不确定，一些数据表明它们作用于γ-分泌酶，而另一些数据则支持它们与淀粉样前体蛋白结合。在本文中，我们通过基于荧光共振能量转移的检测方法来解决这一争议，以研究在没有淀粉样前体蛋白和Notch等天然底物的情况下，γ-分泌酶调节剂是否会改变完整细胞中早老素-1/γ-分泌酶的构象。我们报告γ-分泌酶变构位点位于γ-分泌酶复合物内，但γ-分泌酶调节剂需要底物对接才能进入该位点。
